Speaker
Description
Current gravitational wave detectors (GWDs) are sensitivity limited by mirror coating thermal noise (CTN). Despite decades of research, GaAs/AlGaAs crystalline coatings are the only coating candidate that has demonstrated a CTN that is capable of meeting the sensitivity goals of LIGO A+ and LIGO A#. These substrate-transferred crystalline coatings exhibit the lowest measured CTN both at room and cryogenic temperatures, while demonstrating optical performance on-par with the best ion-beam sputtered multilayers. The most significant challenge in deploying this coating technology in full-scale GWDs has been the ability to produce the coating at sizes greater than 20 cm diameter.
We will provide updates on a new production process for AlGaAs mirror coatings at 30 cm. Efficiencies include the production of GaAs seed wafers grown on 30 cm Ge, the retooling of MBE facilities to 30 cm, and the bonding of 30-cm coatings to fused silica substrates. Each of these steps is currently being tested separately and the combined production of the first 30-cm AlGaAs coatings will commence with the availability of high-quality AlGaAs multilayers on Ge.